U.S. Pat. No. 3,778,458 discloses lactone-silicone block copolymers useful as surfactants and/or as foam stabilizers in the manufacture of foamed, cellular polyurethane materials. The copolymers described therein appear to be non-linear graft structures which apparently are not readily modifiable to form thermoplastic or linear block copolymers. The purpose of the foam stabilizer as taught in that patent is to assist in the production of foam during the formulation of the foam composition and to prevent the collapse of the foam until the foam product has developed sufficient gel strength to become self-supporting.
U.S. Pat. No. 3,372,356 discloses organosiloxane polyamide block copolymers alleged to be useful as additives to nylon products to impart a lower coefficient of friction to the nylon and to impart improved bonding characteristics of the nylon to glass.
French Pat. No. 2,168,221 apparently discloses the production of polycaprolactone-polysiloxane blocks by reacting an isocyanate-terminated polycaprolactone with a siloxane. However, the chemistry as described in the French patent would not appear to result in the described products.
None of the additives disclosed in the above-discussed patents are disclosed as being useful for modifying the surface properties of a variety of other polymers (base polymers) when used in blends. Furthermore, none of the additives disclosed in these patents may be permanently incorporated into a linear polymer system useful for modifying surface properties of that system. Therefore, there is a need to discover additives which can be used to blend with base polymers, which base polymers have known and desirable physical and bulk characteristics for specific purposes, but which have surface properties, which for one or more reasons, render them impractical or useless for other applications. For example, there are many polymers which have physical and bulk properties which would render them useful for prosthetic devices, catheters, or other items which could be implanted in the human body. However, the surface characteristics of most polymers are not compatible over a long term in a biological environment, such as when in constant contact with blood. Another example of this problem is in the field of water repellent synthetic textiles for recreation or industrial clothing. While most synthetic polymers are hydrophobic and therefore the coatings would repel water, it would also be desirable for the textile to have sufficient anti-blocking characteristics to provide facile slippage of one piece of fabric over another. There are many other examples where the bulk and physical characteristics of a particular polymer might make it desirable for certain uses, particularly in view of the fact that most polymers are relatively inexpensive to make compared to other construction materials, but where the polymers are rendered inapplicable due to their surface properties.
It is therefore an object of the present invention to provide a novel class of linear polysiloxane-polylactone block copolymers which may be used as additives to modify other polymers (base polymers) rendering a blend thereof useful for various applications.
It is another object to provide novel linear polysiloxanepolylactone block copolymers which are useful as prepolymers for chemical incorporation in situ into base polymers during polymerization to form such base polymers.
The present invention describes linear polysiloxane-polylactone block copolymers which are useful as surface modifying additives when blended with polyurethanes, polyureas, polyvinylchloride, polyamides, epoxy or phenoxy resins, polyesters, polyester-polyether copolymer acrylonitrile-butadiene-styrene (ABS) and styrene-acrylonitrile (SAN) resins, polycarbonates, styrene-maleic anhydride copolymers, polymethyl methacrylates, polyolefins, and many other polymeric materials. The linear polysiloxane-polylactone block copolymers of the present invention may also, for example, be further reacted with diisocyanates and other commonly employed polyether or polyester soft segments, and with low molecular weight diols or diamines to produce segmented, thermoplastic polyurethanes (ureas).
Also, the block copolymers according to the present invention can be reacted into epoxy resins cured with anhydrides through pre-reacting the linear block copolymers with the anhydride. These are useful as surface-modifying additives and to decrease water uptake in the epoxy resins. Furthermore, the copolymers according to the present invention can be reacted into polyamides derived from .epsilon.-caprolactam through pre-reacting the linear block copolymers with a diisocyanate to provide useful surface-modifying additives. Additionally, the copolymers according to the present invention are useful as additives to polyethylene terephthalate to increase the crystalization rate.